What is the purpose of an economizer in eligible HVAC systems?

• A. To recirculate indoor air
• B. To use outdoor air for cooling when conditions are favorable, reducing mechanical cooling demand.
• C. To humidify the air
• D. To filter air

Answer: (B)

An economizer is meant to take advantage of favorable outdoor conditions to cool the space without relying on mechanical cooling. When outdoor air is sufficiently cool (and acceptable in humidity and quality), the system brings in outside air and uses it to lower the indoor temperature, which reduces the need for running compressors and other cooling equipment. This is often done with dampers and sensors that decide when outside air can provide cooling benefit. When outdoor conditions aren’t suitable, the system shuts the economizer and recirculates indoor air to maintain comfort while the mechanical cooling handles the load. This approach saves energy and lowers operating costs, especially in milder climates. Humidification or filtration aren’t the primary purposes of an economizer; recirculating indoor air is what happens when outside air isn’t used.